Electric switch



4 Sheets-Sheet l W. J. HUDSON ELECTRIC SWITCH Filed Dgo. 10, 1958 Sept.16, 1941.

Sept. 16, 1941.

- Filed De G. 10, 1938 w. J. HUDSON 2,255,886

ELECTRIC SWITCH 4 Sheets-Sheet 2 INVENTOR Spt. 16, 1941. w. HUDSON IELECTRIC SWITCH Filed Dec. 10, 1958 4 Sheets-Sheet 5 5 "ill ll: 1-

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. MM M w m f i M5 m 7 z hwm z Z W? WM W M y 09/ I/IMHKU Sept. 16, 1941.w. J. HUDSON ELECTRIC SWITCH File-d Dec. 10, 1938 4 Sheets-Sheet 4INVENTOR J05 flafsarz BY A TTORNEV Patented Sept. 16,1941

ELECTRIC SWITCH William John Hudson, Milwaukee, Wis auignor to Square DCompany, Detroit, Micln, a corporation of Michigan Application December10, 1938, Serial No. 245,011

8 Claims.

ment of the are straight upward. Any production of arcs and magneticfields having the same relative directions as described above willalways result in a motion ofthe arc perpendicularly to a the point ofinitiation; there will be no tendency on the part of the magnetic fieldto produce any motion other than the one described. Thus, if the arechances to be drawn at the extreme edge of a contact, its path will bealong this extreme edge as it travels upward and the tendency will b tomelt and vaporize more contact material than if the path were along thecenter of the contact, for a sharp edge is more easily heated than aflat surface. A magnetic field such as observed above acting upon an arcbowing outward in a horizontal plane cannot influence it so as toproduce a sidewise motion and cannot prevent the arc from impinging uponthe surfaces of the confining insulating barriers; the arc strikingthese insulating barriers will often result in the gradual burning awayof the barrier material in the regions opposite the contacts.

An object of this invention is to control the path of the arc and tohold the are centrally of contacts and are chute so as to preventcontact by it with the supplementary parts and thus materially lessenthe possibility of damage to said elements.

According to the present invention, the control of the arc position isattained by the production of a magnetic field having curved lines offorce in the region of arc initiation, the concavity of said curvedlines being directed upward.

Since the motion imputed to the are by the magnetic field is everywhereperpendicular to the direction of the lines of force, it is apparentthat with a magnetic field composed of curved lines of force a lateralcontrol of the arc is obtained. The curved lines of force impel the arctoward the center of the concavity of the magnetic field regardless ofpoint of initiation. Thus a definite bias is given the are away from theit travels upward, consequently resulting in less burning of thecontacts, elimination of burning of the barrier material and a moreefllcient rupturing of the arc.

Another object or the invention is to provide an improved and moreefilcient form of magnetic blowout device for an electric contactor.

Another object of the invention is to increase the arc-rupturingcapacity of a contaotor by the provision of a magnetic blowout havingrugged and simple means for laterally controlling the arc.

Another object is to provide for longer life of the contacts andinsulating barrier or chute in an electric contactor by lateral controlof arcs drawn between the contacts.

Another object of the invention is to provide an arc chute mountedbetween the side plates of a magnetic blowout and having two L-shapedbrackets fitted. into recesses in the sides and near the lower edgethereof; the brackets together with the through bolt connecting themproviding a magnetic path which affects and distorts the magnetic fieldbetween the side plates to impart a definite curvature thereto.

Another object of the invention is to provide a magnetic blowout havingsplit side plates; the, side plates having an upper and lowerextensions, with the upper extensions serving as main pole pieces forthe blowout coil and the lower extension carrying auxiliary coils woundin a direction which will provide a magnetic potential that 'opposesthat of the main coil; the flow oi the flux from the upper extensionswith their higher magnetic potential to the lower extensions with theirlower -magnetic potential creating a distorted magnetic field which willprovide lateral control of the arc.

Another object of the invention is to provide a magnetic blowout havingauxiliary plates disposed-upon a blowout core with the auxiliary platesincluding less turns of the blowout coil therebetween. The number ofturns 01' coil corresponding to the sections into which the auxiliaryplates divide the core determine the relation of the magnetic potentialsof the auxiliaryv side plates to each other and to the main side plates.The combined magnetic field will be one provided with curved lines withthe concavity upward to obtain lateral control of the arc.

Other objects and features of the invention will be readily apparent tothose skilled in the art from the following specification and appendeddrawings illustrating certain preferred edges and toward the center ofthe contacts as embodiments of the invention in which:

, plate a, as by a ship's,

, stud 9. About the core Figure l a side clcvational view of an elec= Iv t wir the ventto is a it (devotional viewoi the con= taster.

figure 3 is a deta ded scctio view on the line m-m or Figure 2.

aasaaco ature into its pivot and also for rotation to its extreme ofiposition.

mgidly mounted on the back plate is a" conducting portion 29 insulatedfrom the L= Figure o is an enlarged, detailed sechonal view of a modifieFi 8 is J? on or the modification oi Figure it.

Figure 9 is an alternative achemahc diagram tor the or? ary colls'ofthemodification oi ""111: 5.

File id is a sideelevatlonal view of another mention at the vmtion.

Figure 11 is a front elevational view of the rncation shown in Figureit.

Mo e is is a ttom' view of the rnodiflca= tion shown in Figure no.

In the preferr term of the invention illus= trated in l es 1-4 inclve,there is shown a supporting plate i, upon which is mounted a stationarycontact t 2, which adjustably carries a contact holder 8, hag rncuredthereon a stationary contact d Rlgidly secured to the is an operating etassembly formed by} an L-sha piece 6 and a cylindrical core ll,terminating at the pole piece 8 which is secured to the core l by meansof a l is disposed an energizing coil i0 forefiecting the switchingoperation of the contactor parts. Located at tho front of the operating.magnet'is an armature member Ii. Rigidly connected to the armaturemember H are a'pair of generally i.-shaped brackets l2 and I 3. Thefront faces of the brackets l2 and is are provided with flanges it-and IB spaced from each other to guide a contact carrying finger It. Theflanges i4 and it are notched to receive a rocker pin I! which iselongated in cross-section and received in said slot, is limited to adisassembling movement parallel to the slot. L

A spring guide I. is rigidly mounted on armature member H and isreceived within an enlarged opening in the contact carrying finger It.A-

notch IS in the back face of the finger it receives the forward portion01 the rockerpin H to form a. fulcrum or axis for rotation of the'contact carrying finger relative to the armature. A compression springis disposed about the spring guide" biasing the finger toward thearmature and is maintained in place by av washer 2| and a pin 22 on thespring guide ll.

- -An adjusting screw 23 threaded into the finger l8 and bearing againstthe armature H and havshaped magnetic member it by an -atlng sheet 86.The conducting portionfid is provided with arms Eli which engage thehack ends of the brackets i2 and ill when the armature assembly is inits extreme on position. The conduct= ing portion and the arms at form arigidly mounted massive abutment engaged by the brackets it l8, rigidwith the ature ii, to absorb the shock incident to the abrupt stoppingof the armature in its extreme position. A stud 82 which mounts theconducting portion 29 extends through to the back of plate 1. and isadapted to be put in conducting relation with a lie rm.

A woven flexible conducting web 33 is rigidly coected at one end to thecontact cars ger it and extending beneath the magnetic circuit andarmature biasing sp has its other end rigidly connected to 29,-by meansof a stud 86.

The conducting portion at is provided witha generally central opening 85in which is disposed an insulating guide to receiving and guiding thefree and ti of the spring guide pin 2t. thus guiding the movement ofthis end of the pin in response to movement or the armature member itupon cnergization or deenergization of the coil id.

Upon the supporting plate 8 is mounted an upper terminal to havingconnected thereto one the contact holder 3 is an arc horn til which alsoserves as a mechanical support for an insulating gases to an upward anding a locking nut 24 is provided for varying the normal position oi thecontact carrying finger 4 relative to the armature. A movable contact 25is mounted at the end of contact finger IS in position to cooperate withstationary contact 4.

Beneath the operating magnet and passing.

through the face of brackets I 2 and II, spring guides 26 are providedhaving compression springs -21 disposed thereupon. The compressionspring 21- exerts a biaslngtorce on the spring guide 2! and the bracketsl2 and I! which for arc chute 4|. chute 4| and on are pivoted abouttransverse pin 28 to bias the 5 arc chute ti about the cooperatingcontacts.

The are chute 66 is formed 01 joined halves of refractory insulatingmaterial and serves to confine the arc and to limit the direction of thehot outward motion through the provided opening 42 in the face of thearc chute. The arc chute is provided at its sides and near the loweredge thereofwith recesses into which two L-shaped brackets 43 arefitted: a through bolt definitely holds the'brackets 43 against motionin any direction.

The brackets 43 serve as clamps to secure the segments of the arc chute4i togethen Each bracket '48 is provided at the end thereof nearest thecontacts 4 and 25 with athin non-magnetic piece 45, said piece 45 beingdirected upward and serving to secure in place a removable insulatingdisc 46; this'disc 46 being so disposed as to facilitate, the use of thebest refractory insulating material at the points of greatest heating.

The movable contact 25 is provided with an arc horn 41 to lessen damageto its retaining stud.

Within the blowout coil 39 is a cylindrical core 48 having. attached toits opposite ends a pair of horizontally'spaced s1dep1ates-49 ofmagnetic material which vact as pole pieces for the blowout flux and aredisposed, as shown, at the opposite sides of the arc chute andcooperating contacts and also serve as additional mechanical supports Atthe upper edge of the arc the sides thereof is provided a ledgeformation which rests upon side plates '43 and tends to support arechute 4| in position. The blowout assembly is rigidly secured to thecontact post 2.

The are chute H is mounted in position intermediate the side plates 49otthe blowout magnet.

. :4 not shown, at the back of the insulat= ins Plate i.

the conducting portion v The L-shaped brackets 43 are fitted in recessesat the sides and lower edge thereof of the arc chute 4|; the topsurfaces or the brackets, so positioned, are directly below and at arelatively short distance from the lower edges of the side plates 49.The brackets 43 and the through bolt "44 are constructed of magneticmaterial and provide a low reluctance magnetic path. The

presence of a magnetic path of this type adjacent to the magnetic fielddisposed between side plates 49, which normally is composed ofhorizontal lines of force, will affect the latter field to cause thenormal magnetic field to become distorted and to assume the formindicated in Figure 4.

It the arc is initiated at the center of the contact as at A in Figure4, it will be forced straight upward on the lines of force. If it isinitiated at the edge of the contact as at B or C, the force acting uponit will be perpendicular to the direction of the lines of force at suchpoint and the arc will thus be driven toward the center of the air spaceas well as being forced upwardly. If the central part of the arc shouldbow outward to a point D or E beyond the contacts, it would be forcedback to the center of the space between the contacts by the action ofthe lines I of force.

It is readily apparent that the magnetic bracket and bolt assembly couldbe replaced by a single magnetic U-strap or combination of differentlyshaped magnetic pieces if properly located to give a similar magneticeffect, and could be supported otherwise than by the arc chute withoutdeparting from the spiritof the invention.

Figures 5 to 7 inclusive illustrate a modification of the invention. Theside plates 49 and the L-shaped brackets 43 with the through bolt 44 ofthe preferred embodiment being replaced by a split side plate 5|provided with upper and lower extensions 52 and 53; the upper extensions52 serving as main pole pieces for the blowout coil 39, and the lowerextension 53 are adapted to carry auxiliary coils 54 and 55. Theauxiliary coils 54 and 55 are wound about the lower extension 53 in sucha direction as to set up a magnetic potential which opposes that of themain coil within their common magnetic path..

Thus the lower extension 53 of each pole is at a lower magneticpotential than the upper extension 52 and the flux will flow from theupper extension 52 to the lower extension 53 creating a field formsimilar to that shown in Figure 4 and producing the same effect upon anare as does the preferred embodiment. Coils 54 and 55 may be designed soas to carry the full load current and are then to be connected in serieswith each other and with the main blowout coil as depicted in Figure 8.Or, if cois 54 and 55 are designed to carry but half the load current,they are then'connected in parallel with each other and in series withthe main coil as shown in Figure 9. By varying the design of the coils54 and 55, the amount of distortion of the field can be regulated.

Figures 10 to 12 inclusive illustrate another modification. The sideplates 58 are essentially the same as side plates 49 used in thepreferred embodiment. But here the blowout core 48 is formed of threesections, the two outer provided with openings generally centrallythereofv and the center section being provided with generally centrallythreaded holes at each end'thereof to receive studs 51. Auxiliary sideplates 58 are inserted between turns of the blowout coil 39 and attachedto the core. 45 at point of jointure of core segments by means of thestuds 51 which pass through the holes through the outer core sectionsand through openings in auxiliary side plates 58 and are received by thethreaded openings in the center core portions.

The relation of the magnetic potentials of the auxiliary side plates 58to each other and to the main side plates 58 is determined by the numberof turns of coil corresponding to the three sections into which theblowout core 49 is divided by the insertion of the auxiliary plates 58.The combined magnetic'field obtained will be of the same general shapeas shown in Figure 4 and performing the same function and producing thesame effect as the magnetic field described in the preferred embodiment.The degree of distortion can be controlled by variations in design ofthe coil and magnet parts.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto as many variations will be readily apparent to thoseskilled in the art and the, invention is to be given its broadestpossible interpretation within the terms of the following claims.

What is claimed is:

1. In an electric circuit controlling device, a pair of contacts, meansto move one of said contacts relative to the other to eiiect opening andclosing, an arc chute disposed about said contacts, a bowout coil toproduce a magnetic flux about said contacts to effect a blowing out ofany drawn arc, and a low reluctance magnetic path provided by agenerally U-shaped magnetic circuit so disposed about the contacts as toproduce a distortion downwardly of at least some of the normallyhorizontal lines of force adjacent to the contacts so as to bias thedrawn arc to the center of the arc chute.

2. In an electric controlling device, stationary and movable contacts,means for effecting movement therebetween, magnetic pole pieces atopposite sides of said contacts, a blowout coil producing a magneticfield between said pole pieces for the expulsion of any are drawnbetween said contacts, and a generally U-shaped magnetic circuitdisposed about the contacts beneath said pole pieces so as to produce anupward concavity of the normally horizontal lines of force of themagnetic field in the region of the contacts so as to impart a lateralbias to the drawn are.

3. In an electric circuit controlling device, relatively movablecontacts, means for moving the contacts to effect switching operation,an arc chute disposed about said contacts and having an opening in theface thereof to provide for the escape of formed gases, a blowoutstructure including magnetic pole pieces attached to a magnetic coreabout which a series coil is wound to produce a normally transversemagnetic field to obtain expulsion of any are drawn between saidcontacts, and a low reluctance magnetic path including pole piecesdisposed below the bottom edges of the side-plates and distorting thenormally horizontal lines of force of the-magnetic field downwardly soas to bias the are not only upwardly but also laterally.

4. In an electric circuit controlling device, a pair of contacts, meansto move one of said contacts relative to the other to effect opening andclosing of the circuit, main magnetic pole pieces at opposite sides ofthe contacts, a blowout coil to produce a magnetic flux between saidpole pieces for blowing out an are drawn between the com tacts and meansmagnetically connected to said pole pieces and having auxiliary polepieces at different magnetic potentials than said main pole pieces toproduce an auxiliary flux between said main and auxiliary pole pieces to'efiect a distortion of the main flux whereby lateral control of the arcis secured.

5. In an electric circuit controlling device, sta tionary and movablecontacts, means for eiiecting relative movement therebetween, a magneticcore, a blowout coil wound thereupon to produce a magnetic field for theexpulsion of any arc drawn between said contacts, main magnetic polepieces attached to said core and extending at opposite sides of saidcontacts, and auxiliary pole pieces attached to said main pole piecesand carrying auxiliary coils efiecting a diflerence in magneticpotential between said main and auxiliary pole pieces and producingauxiliary fields therebetween whereby the normal field between said mainpole pieces is distorted, at least in the region of the contacts, andlateral control of any arc drawn between the contacts is secured.

6. Inan electric circuit controlling device, relatively movablecontacts, means for effecting relative movement between said contacts toefiect' switching operation, an arc chute disposed about said contacts,a magnetic core, a blowout coil wound thereupon producing a magneticflux coils wound about the lower arms of said split side'plates andproducing local magnetic flux between the upper and lower pole pieces ofeach side plate to distort downwardly the normally horizontal lines offorce at least adjacent to the contacts so as to bias the drawn arc tothe center of the are chute.

7. In an electric circuit controlling device, stationary and movablecontacts, means for effecting movement of the movable contact to openand close the circuit, a magnetic core, a blowout coil wound thereuponto produce a magnetic field for the expulsion of any are drawn by thecontacts, main side plates secured to the magnetic core disposed atopposite sides of the contacts, and auxiliary side plates embracing lessturns of the blowout coil disposed upon the magnetic core and extendingadjacent to the main side plates, the said less turns producing adifference in magnetic potential between said main and auxiliary sideplates to establish local magnetic fields therebetween and efiect adistortion of the normal transverse field between the main side plateswhereby a lateral bias is imparted to any arc drawn between thecontacts.

8. In an electric circuit controlling device, a pair of contacts, meansto move one of said contacts relative to the other to effect opening andclosing of the circuit, an arc chute disposed about said contacts, amagnetic core, a blowout coil wound thereupon to produce a magnetic fluxabout said contacts to effect a blowing out of any arc drawntherebetween, main side plates secured to the magnetic core and disposedat opposite sides of the contacts, and auxiliary side plates secured tothe magnetic core and embracing a less number of turns of the blowoutcoil to

